JPH046734Y2 - - Google Patents

Description

[Detailed explanation of the idea] Technical field The present invention relates to a blood pressure measuring device.

BACKGROUND ART Conventionally, blood pressure measuring devices have been provided that measure blood pressure values of a living body by compressing a part of the living body with a cuff. Such blood pressure measuring devices generally use a pulse sensor to detect pulse sounds generated from a part of the living body compressed by a cuff (so-called Korotkoff sounds), and determine the blood pressure value based on the generation and disappearance of the pulse sounds. A pulse wave sensor detects pressure vibration waves (pulse waves) of the cuff that are generated in synchronization with the pulse of the living body, and determines blood pressure based on changes in the magnitude of the pressure vibration waves. An oscillometric method for determining the value is known.

Problems to be solved by this invention However, in such a blood pressure measuring device, noise increases when blood pressure is measured using the K-sound method due to the rubbing noise of the subject's clothing, or when the subject's arm is bent. Pressure oscillation waves generated in the cuff due to such factors may be mixed in as noise when blood pressure is measured using an oscillometric method. In such cases, blood pressure values often cannot be sufficiently reliable and remeasurement is often necessary to confirm blood pressure values.

Means to Solve the Problems The present invention was developed against the background of the above-mentioned circumstances, and its gist is that as shown in the complaint correspondence diagram in Figure 6, a part of the living body is cuffed. A blood pressure measuring device that measures the blood pressure value of a living body by compressing the living body, the device comprising: (a) a pulse sound sensor that detects a pulse sound generated from a part of the living body; (b) a pulse wave sensor that detects a pressure oscillation wave generated in the cuff in synchronization with the pulsation of the living body; (c) a second blood pressure determining means that determines the blood pressure value of the living body based on a change in the size of the wave; Based on what exceeded
(d) a first noise discriminator for discriminating whether or not the signal detected by the pulse sound sensor includes noise; (e) if noise is determined by the first noise determining means, the second blood pressure determining means; blood pressure value selection means for selecting the blood pressure value determined by the first blood pressure determination means, and selecting the blood pressure value determined by the first blood pressure determination means when noise is determined by the second noise determination means. .

Action and Effect of the Invention By doing this, in the blood pressure value selection means,
When noise is determined by the first noise determining means, the blood pressure value determined by the second blood pressure determining means is selected, and when noise is determined by the second noise determining means, the first blood pressure determination is performed. Since the blood pressure value determined by the blood pressure determination means is selected, even if noise that affects one blood pressure determination means occurs during blood pressure measurement, a reliable blood pressure value can be measured by the other blood pressure determination means. It is possible. Therefore, re-measurement to confirm the blood pressure value is almost eliminated.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing a control circuit of a blood pressure measuring device to which the present invention is applied, and 10 is a cuff that is wrapped around the upper arm of a human body. The cuff 10 is equipped with a pressure sensor 12, an air pump 14, a throttle 16 and a solenoid valve 18 for slow exhaust, and a solenoid valve 20 for rapid exhaust.
They are connected to each other via 2. The pressure sensor 12 sends a pressure signal SP representing the pressure inside the cuff 10 to a low pass filter 24 and a band pass filter 2.
Supply to 6. The low pass filter 24 is a pressure signal
A cuff pressure signal representing the pressure of the cuff 10 is obtained by discriminating a signal representing a steady pressure contained in SP.
SK is supplied to the CPU 30 via the A/D converter 28. The bandpass filter 26 is, for example, 0.1
A pulse wave signal SM representing a pulse wave is supplied to the CPU 30 via the A/D converter 32 by passing a signal having a frequency component of about ~10 Hz and discriminating the pulse wave signal included in the pressure signal SP. . This pulse wave is a pressure vibration wave generated within the cuff 10 in synchronization with the heartbeat, and is used in determining blood pressure using an oscillometric system, which will be described later. Therefore, in this embodiment, the bandpass filter 26 functions as a pulse wave sensor. Further, the pressure sensor 12 sends the pressure signal SP to the CPU via the A/D converter 34.
Supply to 30. Through this A/D converter 34
The pressure signal SP supplied to the CPU 30 is
It represents the pressure (absolute value) of In this embodiment, as will be described later, whether or not noise is mixed into the pulse wave signal is determined based on whether or not the pressure change value (absolute value) A of the cuff 10 has become larger than the set value Aα. Therefore, the pressure signal SP is used for noise discrimination.

On the other hand, inside the cuff 10 there is a microphone 36.
is provided. The microphone 36 functions as a pulse sound sensor in this embodiment, and detects the pulse sound (Korotkoff sound) generated from the upper arm of the subject and generates a pulse sound signal SO representing the pulse sound.
is supplied to the bandpass filter 38. In this embodiment, the microphone 36 functions as a pulse sound sensor. The band filter 38 is, for example, 30 to 80
A signal having a frequency component on the order of Hz is passed through, and the passed pulse sound signal SO is supplied to the CPU 30 via the A/D converter 40.

The CPU 30 connects to the ROM via the data bus line.
42, RAM 44, display 46, and output screen interface 48, and ROM 42
RAM 44 according to the program stored in advance.
The air pump 14 and the solenoid valves 18 and 20 are controlled by executing signal processing while utilizing the memory function of the controller.
Further, the CPU 30 executes a series of blood pressure measurement operations, determines the blood pressure value by the oscillometric method based on the pulse sound signal SM, the cuff pressure signal SK, etc., and determines the blood pressure value by the K sound method based on the pulse sound signal SO. The blood pressure value is determined, and the one unaffected by noise among the blood pressure values obtained by both methods is displayed on the display 46.

Hereinafter, the operation of this embodiment will be explained according to the flowcharts shown in FIGS. 2 to 5.

When the power is turned on, initial processing at step S1 is executed. Next, step S2 is executed to determine whether the measurement start pushbutton switch 50 has been operated. When the switch 50 is not operated, step S2 is repeatedly executed and the standby state is set, but when the switch 50 is operated, step S3 is executed and both the solenoid valves 18 and 20 are closed. At the same time, the air pump 14 is started. In the following step S4, it is determined whether the cuff pressure P exceeds a predetermined constant target cuff pressure Pm. This target cuff pressure Pm is a pressure that is sufficiently higher than the systolic blood pressure value, for example, a value of about 180 mmHg.If the cuff pressure P has not yet exceeded the target cuff pressure Pm, steps S3 and S4 are repeatedly executed; When pressure P exceeds target cuff pressure Pm, step S
5 is executed, the air pump 14 is stopped, the solenoid valve 18 is opened, and a gradual pressure reduction of the cuff 10 is started. In the following step S6, flag FA and flag FK are each cleared to 0. When the flag FA is 1, it indicates that noise (pressure oscillation waves) that affects blood pressure measurement using the oscillometric method has occurred, and when the flag FK is 1, it indicates that K
This indicates that noise has occurred that affects blood pressure measurement using the sound method. Next, step S
By executing the blood pressure measurement routine in step 7,
In the process of lowering the cuff pressure P, the systolic blood pressure value and the diastolic blood pressure value are measured by the oscillometric method and the K-sound method, respectively. FIG. 3 is a diagram showing this blood pressure measurement routine. First, step SS
1 is executed to determine whether or not the pulse wave signal SM has been detected. If this judgment is denied, the following steps SS2 and SS3 are skipped, but if the judgment of step SS1 is affirmed, in the blood pressure value determination routine of the subsequent step SS2, the pulse wave represented by the pulse wave signal SM is skipped. A so-called oscillometric blood pressure determination algorithm for determining the systolic and diastolic blood pressure values based on the change in magnitude is carried out, thereby determining the systolic and diastolic blood pressure values. Therefore, in this embodiment, the pressure sensor 12, the low-pass filter 24, the high-pass filter 26, and the step SS1 are
and SS2, etc. correspond to the second blood pressure determining means.
Next, by executing step SS3,
These blood pressure values are stored in RAM44. next,
Step SS4 is executed to determine whether the pulse sound signal SO has been detected. If this judgment is denied, subsequent steps SS5 and SS6 are skipped, but if this judgment is affirmed, steps SS5 and SS6 are skipped.
In the SS5 blood pressure value determination routine, the pulse sound signal
A K-sound blood pressure determination algorithm is executed to determine the systolic blood pressure value and the diastolic blood pressure value based on the occurrence and disappearance of SO, thereby determining the systolic blood pressure value and the diastolic blood pressure value. Therefore, in this embodiment, the microphone 36,
The band filter 38, steps SS4 and SS5, etc. correspond to the first blood pressure determining means. Next, these blood pressure values are stored in the RAM 44 by executing step SS6.

After the blood pressure measurement routine is executed as described above, step S8 is executed to determine whether the measurements of the systolic blood pressure value and the diastolic blood pressure value by the oscillometric method and the K-sound method have been completed. If this judgment is negative, steps S6 to S8 are repeatedly executed.
If the determination in step S8 is affirmative, the subsequent step S9 is executed to open the solenoid valve 20, thereby rapidly exhausting the pressure inside the cuff 10.

Here, what is shown in FIGS. 4 and 5 is a case in which, for example,
This is an interrupt routine that is executed periodically with a short cycle of about 10ms. In the interrupt routine shown in FIG. 4, first, step SA1 is executed so that a change value A (absolute value) representing the magnitude of change in cuff pressure P is sequentially changed based on a signal from the A/D converter 34. It is determined. Next, step SA2 is executed to determine whether the change value A is larger than a predetermined set value Aα. This set value Aα is larger than the maximum pulse wave, and is set to about 15 mmHg, for example.
If this judgment is negative, the flag FA is maintained at 0, but if the judgment at step SA2 is affirmative, the flag FA is set to 1. The case where the flag FA becomes 1 is, for example, when the subject's arm is bent during blood pressure measurement. Therefore, in this embodiment, the step SA2 corresponds to the second noise determining means for determining whether or not noise is mixed in the pulse wave signal.

on the other hand. In the interrupt routine of FIG. 5, first, step SK1 is executed to obtain the input signal level obtained through the microphone 36.
NK is determined based on the signal from A/D converter 40. This input signal level NK is the signal strength (for example, effective value or signal power) of a predetermined section of the input signal obtained through the microphone 36. Next, step SK2 is executed and the input signal level NK is set to a predetermined set value Nα.
It is determined whether the This setting value Nα
is a predetermined value that is sufficiently large so that the maximum value of the pulse sound periodically generated from the artery does not exceed even if it is included in the predetermined interval for calculating the input signal level. Therefore, in this embodiment, the step SK2 corresponds to the first noise determining means for determining whether noise is mixed in the input signal of the microphone 36. If the judgment at step SK2 is negative, flag FK is maintained at 0, but if it is affirmative, flag FK is set to 1. When this flag FK becomes 1,
For example, this may occur when a sound is heard from the clothing of the person being measured.

Returning to FIG. 2, when step S10 is executed following step S9, it is determined whether either flag FA or flag FK is 1. If this determination is affirmative, step S11 is executed and it is determined whether the flag FA is 1 or not. If the determination at step S11 is negative and it is determined that the flag FA is not 1,
Since no noise is mixed in when blood pressure is measured using the oscilloscope method, step S12 is executed and the blood pressure value measured using the oscilloscope method is displayed on the display 46. In step S11, flag FA is set to 1.
If it is determined that
3 is executed and it is determined whether the flag FK is 1 or not. This judgment was denied and the flag FK was 1.
If it is determined that the noise is not increased during blood pressure measurement using the K-sound method, the subsequent step S14 is executed and the blood pressure value measured using the K-sound method is displayed on the display 46. If it is determined that the flag FK is 1 in step S13, noise has increased or been mixed during measurement using both methods, so the following step S13 is performed.
15 is executed, and a display indicating re-measurement is made on the display 46. On the other hand, if the determination in step S10 is negative and it is determined that both flags FA and FK are not 1, step S16 is executed and in this embodiment, the blood pressure value measured by the oscilloscope method is displayed. It's becoming like that. Therefore, in this embodiment, step S1
0, S11, and S13 correspond to blood pressure value selection means.

As described above, according to this embodiment, if noise increases when blood pressure is measured using the K-sound method and no noise mixes when blood pressure is measured using the oscilloscope method, and when noise increases or mixes when measuring blood pressure using both methods. If this happens, the blood pressure value measured by the oscilloscope method will be displayed, but noise will be mixed in when measuring the blood pressure by the oscilloscope method, and the K value will be displayed.
If noise does not increase when measuring blood pressure using the sound method, the blood pressure value measured using the K-sound method will be displayed, and if noise increases or is mixed in when measuring blood pressure using both methods, a remeasurement will be displayed. Therefore, even if noise increases or is mixed in when measuring blood pressure using one method, the reliability of the measured blood pressure value will be higher than before by using the blood pressure value measured simultaneously using the other method. In addition, the number of remeasurements when measuring blood pressure is reduced compared to the conventional method. In general, the oscillometric blood pressure determination method is disturbed by relatively low frequency noise such as body movement, while the Korotkoff sound blood pressure determination method is disturbed by relatively high frequency noise such as the sound of cloth rubbing. Although measurements tend to be disturbed by noise,
According to this embodiment, blood pressure measurement values can be accurately displayed without being affected by any of the noise.

In the above-mentioned embodiment, if it is determined that noise is not increased or mixed in when blood pressure is measured using both methods, the blood pressure value measured using the oscilloscope method is displayed. However, this is not necessarily necessary, and the blood pressure value measured by the K-sound method may be displayed, or the blood pressure value measured by both methods may be displayed together.

In addition, various changes may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a control circuit of a blood pressure measuring device which is an embodiment of the present invention. FIG. 2 is a flowchart illustrating the operation of the embodiment shown in FIG. FIG. 3 is a diagram illustrating the blood pressure measurement routine of FIG. 2. 4 and 5 are diagrams each showing an interrupt routine that is executed by interrupting the flowchart of FIG. 2. FIG. 6 is a diagram corresponding to claims of the present invention. 10...Cuff, 26...Band pass filter (pulse wave sensor), 36...Microphone (pulse sound sensor), Steps SS1, SS2...Second blood pressure determination means, Steps SS4, SS5...First blood pressure determination means,
Step SK2...First noise discrimination means, Step SA2...Second noise discrimination means, Step S1
0, S11, S12... (blood pressure value selection means),
SM...Pulse wave signal, SO...Pulse sound signal.

Claims (1)

[Claims for Utility Model Registration] A blood pressure measuring device that measures a blood pressure value of a living body by compressing a part of the living body with a cuff, comprising: a pulse sound that detects a pulse sound generated from the part of the living body; a first blood pressure determining means comprising a sensor and determining the blood pressure value of the living body based on the generation and extinction of the pulse sound; and a pulse detecting means for detecting pressure vibration waves generated in the cuff in synchronization with the pulse of the living body. Equipped with a wave sensor,
a second blood pressure determining means for determining the blood pressure value of the living body based on a change in the magnitude of the pressure vibration wave; and a second blood pressure determining means for determining the blood pressure value of the living body based on a change in the magnitude of the pressure vibration wave; a first noise discriminating means for discriminating whether or not the signal detected by the pulse sound sensor contains noise based on the fact that the cuff pressure change value exceeds a predetermined judgment reference value; a second noise determining means for determining whether noise is included in the pressure oscillation wave based on the fact that the pressure vibration wave exceeds the threshold; blood pressure value selection means for selecting the blood pressure value determined by the means, and selecting the blood pressure value determined by the first blood pressure determination means when noise is determined by the second noise determination means; A blood pressure measuring device featuring: